In U.S. Pat. No. 3,994,239 granted Nov. 30, 1976 and assigned to the assignee of the present application, a head shield extending part way up a railway tank car is disclosed which is adapted to be retrofitted to existing tanks without welding to the tank body. Thus stress relieving of the tank body is not required. A similar design is apparently also disclosed in Railway Age, page 30, Mar. 28, 1977, Vol. 178 No. 6. This patent and article and the references cited therein provide background information for the present invention.
New proposals in Docket No. HM-174 by the Federal Railroad Administration require a shield to extend to the top of the tank. The shield must be at least the size of the entire tank head of the tank car.
For new cars it has been proposed to weld a head shield extending approximately half way up the tank to the base of the tank. See Exhibits A and B found in the present application file. This requires stress relieving of the tank and the shield does not extend to the top of the tank as required by the proposed new FRA regulations, Docket No. HM-174. Furthermore location of the base of the shield to the tank prior to welding is difficult.